Fuel sending units read WRONG time after time!

Here's something that you might try. You might want to "burn" another sender so you have one to screw with.

Carry a can, do whatever, but "get to a place" where the tank is near empty. Drain it through the fuel pickup, on level ground, until you "get air."

Us a good multimeter and carefully measure the resistance of the sender.

Go to a closeby station and fill clear up, drive home, and again on level ground, carefully measure the sender resistance.

You can access this at the rear harness connector in the kick panel if it's easier than crawling under.

Then drive the car or otherwise empty the tank, and yank out the sender.

Now build whatever you need for a jig so you can mount the sender with REPEATABLE results. Scrap wood, whatever

Now move the sender to get the measured resistances that you got above, and figure a way (vertical board, etc) that you can measure the float height and low point. This gives you the physical points of the float at MT and full.

Now with these physical points established, you can bend, lengthen, modify the sender to match as close as you can, the proper full/ MT resistances